1. Field of the Invention
The present invention relates to a retrieving method and apparatuses therefor for video images on the air or video images in a data base or others and more particularly to a video image retrieving method and apparatuses therefor for performing high-speed retrieval by the help of features of video images.
2. Description of the Prior Art
Recently, multi-media information processing systems can store and indicate various types of information such as video and text to users. However, with respect to retrieval of them, a retrieving method using a language such as a keyword is mainly used. In this case, a keyword assigning operation is necessary and it is extremely expensive to assign a keyword to each frame of video having a large amount of information. Furthermore, since a keyword is freely assigned by a data base constructor, there is a problem imposed that when the viewpoint of a user is different from that of the data base constructor, the keyword will be useless. In these circumstances, a request for retrieval from a unique image feature in addition to the keyword is made. However, to retrieve information on the basis of the feature of an image, a high-speed comparison art between the video feature comprising enormous frames and the feature for the queried image is necessary. As a high-speed comparison art only applicable to video images, “Video retrieving method and apparatuses therefor” is proposed in Japanese Patent Application Laid-Open 7-114567. This method does not compare all the frames but compares only an image at the time of changing of cut of images so as to reduce the processing amount. By doing this, the high speed also suited to comparison of images on the air is realized. On the other hand, there is a problem imposed that a scene comprising only one cut or a scene in which the cut change timing varies with editing before or after cannot be compared satisfactorily. Furthermore, during retrieval, scenes other than the scene specified as a retrieval key are not searched in the same way as with other general data base systems, so that whenever scene retrieval becomes necessary, it is necessary to repeatedly compare a very large amount of video information from the beginning thereof to the last. The scene comparison process includes a number of processes such as processes to be performed commonly even if the scene to be retrieved is different as well as the feature extraction and reading processes and repetitive execution of such a process is of no use.